It is well known to the art and to the literature that a chlorinated vinyl polymer referred to as chlorinated polyvinyl chloride, hereinafter CPVC, has excellent high temperature performance characteristics, among other desirable physical properties. Typically, commercial CPVC has in excess of about 57 percent by weight of bound chlorine, and is most conveniently prepared by the chlorination of polyvinyl chloride (hereinafter PVC) as described in U.S. Pat. Nos. 2,996,489; 3,100,762; 3,334,077; 3,334,078; 3,506,637; 3,534,013; 3,591,571; 4,049,517; 4,350,798; 4,377,459; 4,412,898; and 4,459,387, inter alia.
The term CPVC is used herein to define a chlorinated vinyl chloride polymer having in excess of about 58 percent by weight of bound chlorine. CPVC has become an important specialty polymer due to its relatively low cost, high glass transition temperature, high heat distortion temperature, outstanding flame and smoke properties, chemical inertness, and low sensitivity to hydrocarbon feed stock costs. The glass transition temperature of CPVC generally increases as the percentage of chlorine increases. However, a well known undesirable characteristic of CPVC resin is that it inherently has low impact properties, a characteristic which is also common to vinyl chloride homopolymers. Moreover, as the chlorine content increases, the CPVC resin becomes more difficult to melt process, and also becomes more brittle.
The poor melt processability of CPVC resins is exemplified by milling CPVC on a roll mill which results in high torque and high temperatures as well as decomposition of the CPVC. Softening additives or plasticizers have been added to CPVC in order to improve its processability. Although its processability is somewhat improved, these additives produce undesirable effects. Some of the more significant detrimental effects produced by inclusion of these softening or plasticizer additives are lower heat distortion temperatures, softness and weakness in terms of lower tensile strength, and less desirable chemical properties than those exhibited by CPVC alone. These negative attributes of the additives on CPVC limit usefulness of the modified CPVC in the manufacture of rigid plastic articles.
The increasing demand for CPVC pipes, vessels, valve bodies and fittings, and the fact that an impact-deficient CPVC matrix can be improved by compounding and blending it with other polymers, has instigated concerted efforts to develop better impact modified CPVC compositions having increased heat distortion temperatures, and increased ease of melt-processing. Most of these efforts have been channeled toward rigid CPVC applications where acceptable impact strength and dimensional stability under heat are critical. These include the manufacture of exterior structural products, rigid panels, pipe and conduit, injection-molded and thermoformed industrial parts, appliance housings, and various types of containers both large and small.
U.S. Pat. No. 3,264,375 to Robert W. Jones relates to rubber-modified styrene-type polymers and more particularly relates to processes for preparing such materials and for producing rubber-in-monomer solutions to be employed in preparing such materials.
U.S. Pat. No. 3,882,192 to Elghani et al relates to moulding compositions consisting of a) 5 to 95 parts by weight of a polycarbonate, b) 5 to 95 parts by weight of a vinyl chloride polymer, and c) 5 to 95 parts by weight of an ABS graft polymer, a styrene/maleic anhydride copolymer or an ethylene/vinyl acetate copolymer.
U.S. Pat. No. 3,886,235 to Tanaka et al relates to a process for production of vinyl chloride resin composition, by uniform blending of 95 to 70 parts by weight of vinyl chloride resin, and 5 to 30 parts by weight of a modifying component obtained by graft-polymerizing upon a crosslinked copolymer rubber latex a first and then a second grafting component in a sequential two-stage process.
U.S. Pat. No. 3,991,009 to Margotte et al relates to thermoplastic moulding compositions of 1) 70 to 20 percent by weight of graft polycarbonates whose graft stock is a vinyl polymer with a molecular weight of from 10,000 to 100,000, containing from 3 to 10 side chains attached by carbon, each of which contains a hydroxyphenyl group, on which aromatic polycarbonate chains are condensed, and 2) 30 to 80 percent by weight of graft polymer rubbers obtained by polymerizing a mixture of 2.1) 50 to 90 percent by weight styrene, a-methylstyrene, methylmethacrylate or mixtures thereof, and 2.2) 10 to 50 percent by weight acrylonitrile, methacrylonitrile, methylmethacrylate or mixtures thereof on a diene or acrylate rubber.
U.S. Pat. No. 4,105,711 to Hardt et al relates to polymer mixtures consisting of a) 20 to 90 percent by weight of a vinyl chloride polymer; b) 10 to 80 percent by weight of a polycarbonate in which at least 50 percent by weight of the structural units have the formula (1): ##STR1## wherein x is a single bond, O--, --CO--, --SO.sub.2 --, C.sub.1 to C.sub.10 alkylene, C.sub.1 to C.sub.10 alkylidene, C.sub.3 to C.sub.15 cycloalkylene, C.sub.3 to C.sub.15 cycloalkylidene, C.sub.5 to C.sub.20 cycloalkyl alkylidene or ##STR2## and c) up to 100 percent by weight, based on the mixture of (a) and (b) of a rubber.
U.S. Pat. No. 4,173,598 to Castelazo et al relates to processes for making polymeric compositions which have methacrylic and/or acrylic chains grafted onto a copolymerized vinyl diene substrate. The compositions are particularly useful as impact modifiers for polyvinyl chlorides.
U.S. Pat. No. 4,362,845 to Kamata et al relates to a composition with high impact resistance and little fish eyes content, comprising 97 to 60 parts by weight of a polyvinyl chloride-base resin and 3 to 40 parts by weight of a graft copolymer obtained by the three-stage graft-polymerization of 65 to 25 parts by weight of a monomer combination (B) comprising 12 to 57 percent by weight of methyl methacrylate, 1 to 24 percent by weight of at least one of alkyl acrylates having a C.sub.1-8 -alkyl group, 80 to 40 percent by weight of styrene and 0 to 3 percent by weight of a polyfunctional crosslinking agent having one or more alkyl groups in the molecule onto 35 to 75 parts by weight of a butadiene-base elastomer (A) containing 30 percent by weight or more of 1,3-butadiene units.
U.S. Pat. No. 4,399,093 to Kirby et al relates to a method of molding an element from liquid synthetic resin wherein liquid resin is introduced into a mold cavity through a first gate and liquid resin is concurrently introduced into the mold cavity through a second gate with portions of the resin received through each of the gates meeting at a joint interface. The resin in the second gate is caused to solidify sooner than the resin in the first gate so that the leading surface of the resin received through the first gate projects into a leading surface portion of the resin received through the second gate during the mold packing operation to provide an enlarged weld line area and improved strength in the joint.
U.S. Pat. No. 4,443,585 to Goldman relates to impact modifiers having high efficiency at low levels and at low temperatures comprising at least three stages, Stage A being a non-crosslinked polymer of at least 70 percent butadiene and at least 10 percent lower alkyl (C.sub.2 to C.sub.8) acrylate, Stage B being a polymer of at least 80 percent styrene, and Stage C containing at least 50 percent methyl methacrylate and at least 1 percent alkyl (C.sub.1 to C.sub.4) acrylate, the ratio of Stages A:B:C, excluding optional additional stages, being about 70-85:10-15:10-20, the ratio of stages C:B being at least 1, and Stage A being non-agglomerated are disclosed. Also disclosed are methods of preparing the impact modifier and thermoplastic polymer compositions containing the impact modifier.
U.S. Pat. Nos. 4,504,623 and 4,504,624 to Heuschen et al, and assigned to General Electric Company, relate to a method of preparing a polymer mixture and the mixture per se, respectively, wherein the mixture comprises PVC, aromatic polycarbonate, and rubber-like polymers such as ABS, the various acrylates, and the like. The method includes the steps of initially mixing the rubber-like polymer with the polycarbonate at a temperature above 220.degree. C., with the resulting blend being mixed with polyvinyl chloride at a temperature below 220.degree. C.
U.S. Pat. No. 4,617,329 to Weese et al relates to a polymer blend comprising from about 60 parts to about 99.9 parts by weight of a pigmented thermoplastic resin, which resin is a polyester or a polycarbonate or mixtures thereof, and from about 0.1 part to about 40 parts of a sequentially produced multi-stage polymer. The multi-stage polymer comprises a polymer core of at least about 10 parts, based on the weight of the multistage polymer. The core is polymerized from a styrenic monomer, or a mixture of styrenic monomers. The styrenic monomer of the core comprises at least about 50 percent by weight of said core. A second monomer may be present and a crosslinking monomer for styrene is present in said core. The second stage of the multi-stage polymer comprises a polymeric soft stage and the outer stage of the multi-stage polymer is a rigid thermoplastic.
U.S. Pat. No. 4,663,375 to Tamura relates to a process for producing a thermoplastic resin molding which comprises adding to a thermoplastic resin an organic compound which is compatible with said thermoplastic resin to form a homogeneous phase at a molten state of said thermoplastic resin and causes phase separation by cooling, molding the composition by melting, and solidifying it by cooling; and the molding thus obtained.
U.S. Pat. No. 4,680,343 to Biing-lin Lee relates to CPVC/polycarbonate blends containing ethylene-based functional polymers and impact modifiers.
U.S. Pat. No. 4,766,177 to Miller et al relates to adhesion of acrylic polymer coatings to plastic substrates which can be obtained by the addition of an isocyanate modified polyester copolymer to the acrylic polymer coating.
U.S. Pat. No. 4,769,901 to Nagahori relates to a process for producing a PTC device comprising the steps of forming a laminate comprising a PTC composition and at least two electrode plates having the PTC composition sandwiched therebetween, superposing, on the surface of each of the electrode plates of the laminate, a lead plate to be electrically connected to the electrode, joining the electrode plate and the lead plate by spot welding, and during or prior to the spot welding process, forming at least one through hole penetrating through the electrode plate and the lead plate in the center of a weld. This process can minimize the heat damage of the PTC composition and the resulting PTC device has a low contact resistance.
U.S. Pat. No. 4,786,350 to Nesbitt et al relates to a manufacturing process for providing an extruded polyvinyl chloride exterior siding with a weatherable layer of polyvinyl fluoride which is disclosed. In a preferred embodiment, the process facilitates the production of dimensionally stable dark colored siding.
U.S. Pat. No. 4,787,135 to Nagahori relates to a process for producing a PTC device comprising the steps of forming a laminate comprising a PTC composition and at least two electrode plates having the PTC composition sandwiched therebetween, opposing the surface of a lead plate to be electrically connected to each of the electrodes, to the surface of each of the electrode plates of the laminate while contacting at a narrow area, and then passing a current between the electrode and the lead via the narrow contact surf ace to weld them. By this process, there is obtained a PTC device, having, at a portion of the joining interface between each electrode plate and each lead plate, a nugget formed by melting both the plates. This PTC device has a low contact resistance between the PTC composition and the electrode plates.
Thus, it can be seen that the need exists for thermoplastic blends of CPVC and polycarbonate having improved physical properties such as heat distortion temperatures, impact strength, and processability.